Download Chapter 7 - cell

Cell Structure and
Function
Chapter 7
Life is Cellular
Section 7-1
The Cell Theory
1. All living things are composed of cells.
2. Cells are the basic units of structure and
function.
3. All cells come from preexisting cells.
• Who helped to develop theory?
a. Robert Hooke
b. Leeuwenhoek
c. Robert Brown
d. Schleiden and Schwann
e. Rudolf Virchow
Basic Cell Structures
• Most cells contain the following structures:
1. Cell membrane
2. Genetic material (DNA)
3. Cytoplasm
• Two main types of cells:
1. Prokaryotes - no nucleus
2. Eukaryotes - nucleus present
Prokaryotes
• All Bacteria!
• No nucleus but has
DNA
• No organelles
• Has ribosomes
• Always unicellular
• Can move with flagella
or cilia
Eukaryotes
•
•
•
•
•
Nucleus present with DNA
Unicellular or Multicellular
Plants, animals, fungi and protists
Has all major organelles
Can move at unicellular level
Prokaryote vs. Eukaryote
Cell Structures
Section 7-2
Cell Wall
• Found in Plant, fungi, and
prokaryotes.
• Outermost layer, exterior
to cell membrane
• Function: provide
support and protection
• Main component:
CELLULOSE
• Indigestible fiber, used in
making paper
Nucleus and other parts
• Function: controls
cell processes and
contains DNA.
• Chromatin –
chromosomes
clumped together.
• Chromosomes
groups of condensed
DNA
• Nucleolus – small
region inside nucleus,
makes ribosomes,
and RNA.
• Nuclear envelope –
membrane
surrounding nucleus
Centrioles
• Found only in animal
cells
• Function: Involved
in cell reproduction
Cytoskeleton
• Network of protein filaments that helps the
cell to maintain its shape.
• Two Types:
– Microtubules – centrioles, cilia, flagella
– Microfilaments – muscle fibers
Ribosomes
• Function: making
proteins
• Can be found freefloating in the
cytoplasm or bound to
endoplasmic
reticulum.
Endoplasmic Reticulum
• Inter-connected tube system
• Two types: rough and smooth
• Function: Assembly lines to make cell
membrane parts and organic molecules
Rough – assembles and transports proteins
Smooth – assembles and transports lipids
and carbohydrates
Golgi Apparatus & Lysosomes
• Packages proteins
for transport out of
the cell
• Filled with digestive
enzymes
• breaks down food,
foreign bodies and
worn out organelles
Vacuoles
• Function: To store materials which
could be water, food molecules or
waste.
• Plants have a large central vacuole filled
with mostly water.
• Animals have smaller vacuoles usually
called vesicles.
Chloroplasts
• Only found in plant cells.
• Contains own DNA
• Function: Photosynthesis – light
energy is turned into chemical-food
energy.
• Chlorophyll: green pigment ; absorbs and
reflects light.
• Plastids – other pigment containing
organelles (cannot photosynthesize)
Mitochondria
• Function: Release
energy from food
molecules (a.k.a cell
respiration)
• Powerhouse of the
cell
• Contains own DNA
(whose mito-DNA do you
have…Mom’s or Dad’s?)
Figure 7-5 Plant and Animal Cells
Plant Cell
Section 7-2
Vacuole
Smooth endoplasmic
reticulum
Ribosome
(free)
Chloroplast
Cell
Membrane
Ribosome
(attached)
Nuclear
envelope
Cell wall
Nucleolus
Golgi apparatus
Mitochondrion
Nucleus
Rough endoplasmic reticulum
Figure 7-5 Plant and Animal Cells
Animal Cell
Section 7-2
Nucleolus
Nucleus
Nuclear
envelope
Rough
endoplasmic
reticulum
Golgi apparatus
Ribosome
(attached)
Ribosome
(free)
Cell
Membrane
Mitochondrion
Smooth
endoplasmic
reticulum
Centrioles
Movement Through the
Membrane
Section 7-3
Cell Membrane
•
Function: To regulate what enters and
exits the cell; protection and support.
• SELECTIVELY PERMEABLE
• Structures:
a. Phospholipid bilayer – hydrophobic
b. Proteins – gatekeeper for substances
c. Carbohydrates – cell recognition
Figure 7-12 The Structure of the
Cell Membrane
Section 7-3
Cell Membrane
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
Cell Transport Types:
Passive Movement: No
energy required
Active Movement:
Energy required by cell
Diffusion
• Passive
• Movement of a
substance from
high to low
concentration
• Ex: Movement of
O2 and CO2
through
membranes
This is also the same as:
“going down the concentration gradient!”
Osmosis
• Movement of water from high to low
concentration across a selectively
permeable membrane.
(Only permeable to
water)
What determines the direction of water
movement?
• The solute! (what is dissolved in the solvent)
• Solution types:
1. Hypertonic –solute is in high
concentration so water is low.
2. Hypotonic – solute is in low
concentration so water is high.
3. Isotonic – solute concentration is
equal on both sides.
For each beaker, which way will water
move? IN or OUT of the blob cell
Beaker A = isotonic solutions NO MOVEMENT
Beaker B = water will move INTO the cell
Beaker C = water will move OUT of the cell
How do cells cope with osmotic
pressure?
1. Tough cell walls protect from
bursting
2. Contractile vacuoles pump out
excess water in unicellular animals
Many cells cannot cope with osmotic pressure:
*dangerous to drink sea water it will speed up dehydration
(and death) by drinking sea water.
*water injected into you will burst RBC’s
Facilitated Diffusion
• Movement of substance from high to low
concentration across a membrane through a
protein channel.
• Ex: large molecules or ions.
Glucose, neurotransmitters, sodium, potassium
Active Transport
• Require energy for the cell to
complete.
• Movement of molecules from
LOW to HIGH. (against the
concentration gradient)
• Examples: Sodium/Potassium
pump for nerve impulse
condution.
Other Energy Requiring
Transport Methods: Bulk
Movement
• Endocytosis – larger molecules inside
cell, doesn’t need concentration gradient.
1. Phagocytosis - cell eating,
macrophages
2. Pinocytosis – cell drinking
• Exocytosis – removal of large molecules
Endocytosis and Exocytosis
Endocytosis
Exocytosis
Cell Diversity
Section 7-4
Diversity of Cellular Life
• Unicellular Organisms
• Multicellular Organisms
1. Cell Specialization – cells perform
certain functions based on DNA segment
that is turned activated.
2. Levels of Organization
Levels of Organization
Levels of Organization
Section 7-4
Muscle cell
Smooth muscle tissue
Stomach
Digestive system